Vehicle light having a cruciform light distribution

ABSTRACT

In a vehicle lamp, in particular a side marking lamp for a motor vehicle, comprising at least one light source and at least one optical system ( 6   a,    6   b ) arranged in the beam path of the light source, the substantially conical light beam issuing from the light source impinges directly on the optical system ( 6   a,    6   b ) and shines therethrough, wherein the optical system ( 6   a,    6   b ) is such that it produces therefrom a cruciform light distribution ( 3 ).

The invention concerns a vehicle lamp, in particular a side markinglamp, as set forth in the classifying portion of claim 1.

The photometric requirements in respect of side marking lamps of motorvehicles are laid down in national and international regulations andrequirements. They specify inter alia the angular regions from which andthe light intensity with which the light signal must be visible to otherroad users.

In the case of side marking lamps as are used for example on commercialvehicles such as buses and heavy goods vehicles, the minimumrequirements in terms of the visibility range are prescribed for exampleat 10° upwardly and downwardly respectively and 45° towards the left andthe right respectively from a reference axis HV (center line extendingin the direction of radiation) of the lamp. In that respect a uniformminimum light intensity is required in the entire visibility range. Itis only at the center of light distribution that the light intensitymust be markedly higher.

FIG. 1 shows the minimum photometric requirements for a side markinglamp. The window illustrated represents the minimum visibility range ofthe side marking lamp, with a radiation angle, in relation to a centerpoint 5, of 10° upwardly and downwardly, as indicated at 10° U and 10°D, and 45° towards the left and the right, as indicated at 45° L, 45° R.In that respect, a substantially higher level of light intensity of forexample 4 cd is prescribed at the center point 5 (central peak) than inthe region 4 (for example 0.6 cd).

When using LEDs as the light source, satisfying that requirement givesrise to problems as an LED has an irregular, approximately bell-shapedradiation characteristic, with a light intensity which is very high atthe center 5 and which falls off outwardly in a bell configuration. Inthe transitional region between the center 5 and the outer region 4however the light intensity is generally substantially higher than itwould have to be in accordance with the minimum requirements. Therefore,to save on light power, light-refracting optical systems are used, whichproduce a substantially uniformly bright light bar. Such a lamp howevercan be positioned only in one installation position, for examplehorizontally.

Known lamps which can be mounted in different positions (for examplealso turned through 90°) include an optical system which for exampleproduces a circular projection, as is illustrated in FIG. 2 by referencenumeral 1. By virtue of that arrangement, it is admittedly possible forthe lamp to be fitted in different positions (in turned relationship),but a high level of light power is required in order to appropriatelyilluminate the respective projection surface.

That is relatively expensive in the case of an LED as additional lightpower when using LEDs causes a considerable increase in costs, incomparison with incandescent lamps.

Therefore the object of the present invention is to provide a vehiclelamp which can be mounted in positions which are turned relative to eachother through 90° in each case and which is as inexpensive as possibleand which nonetheless satisfies the minimum photometric requirements.

The essential concept of the invention is that of providing a vehiclelamp, in particular a side marking lamp, with an optical system whichproduces a cruciform light distribution. By virtue thereof, incomparison with a circular radiation pattern, a substantially smallerprojection area (namely only a cruciform projection area) is irradiated,and substantially less light power is required for that purpose. It isthus possible to use weaker and therefore more favourable light sources,the light emitted from which is used substantially more efficiently thanin the state of the art.

In addition it is possible for the lamp to be mounted in a plurality ofpositions, preferably in four positions, turned in each case through90°. In the case of a side marking lamp it can be fitted for exampleboth horizontally and also vertically (turned through 90°) to a verticalside wall of a vehicle.

In accordance with a preferred embodiment of the invention the lampincludes 2n LEDs, wherein n is an integer ≧1. With this kind of lightsources, considerable cost advantages are afforded by saving on lightpower.

A possible way of implementing the cruciform light distribution involvesthe use of an optical system of cruciform configuration.

The optical system according to the invention preferably has a centralconverging lens. As a result the level of light intensity at the centerof the light distribution can be additionally increased.

The optical system is preferably arranged in or on a light exit surface,for example a surface formed from transparent plastic material.

A particularly preferred vehicle lamp includes two cruciform opticalsystems, each of which deflects the light incident thereon from thelight source into the one bar of the cross of the cruciform lightdistribution produced thereby more strongly than into the other bar ofthe cross configuration. In accordance with the invention those twooptical systems are positioned in mutually juxtaposed relationship insuch a way that the two ‘light beams’ delivered thereby and each beingof a cruciform cross-section, after passing through a very small nearregion, combine in such a way that, at medium and great distance, theyproduce a single cruciform light spot on a projection surface which isperpendicular to HV. By virtue of the fact that in accordance with theinvention the two optical systems are arranged turned through 90°relative to each other, the above-described asymmetry of the lightdistribution on to the two crossbars of the individual ‘light beams’ iscompletely compensated in the combined overall light beam and thevehicle lamp can be turned in 90° steps without anything being changedin terms of the distribution of intensity of the overall light beamproduced, in the medium or far region.

These and further advantageous configurations and developments of avehicle lamp according to the invention are set forth in the appendantclaims.

The invention is described hereinafter by means of embodiments by way ofexample with reference to the drawing in which:

FIG. 1 is a view of a light distribution for a side marking lamp inaccordance with minimum photometric requirements,

FIG. 2 is a view of a light distribution when using an optical systemaccording to the invention,

FIG. 3 is a plan view of the rear side, which is towards the lightsource, of an optical system according to the invention for producing anasymmetrical, cruciform light distribution,

FIG. 4 shows a view in section through the optical system of FIG. 3taken along line IV-IV,

FIG. 5 shows a view in section through the optical system of FIG. 3taken along line V-V,

FIG. 6 shows a view in section through the optical system of FIG. 3taken along line VI-VI,

FIG. 7 shows a view in section through the optical system of FIG. 3taken along line VII-VII,

FIG. 8 is a plan view similar to FIG. 3 on to the rear side, which istowards two light sources, of two mutually juxtaposed optical systemswhich jointly produce a symmetrical, cruciform light distribution, and

FIG. 9 shows a perspective view of a light cover of a vehicle lamp withan integrated optical system as shown in FIG. 8.

In regard to the description of FIG. 1, attention is directed to theintroductory part of this description.

FIG. 2 shows the circular projection 1 of a light cone as is emitted byconventional vehicle lamps which can be mounted to a vehicle wall bothvertically and also horizontally (that is to say turned through 90°).Because of the relatively large irradiated area the light power requiredin respect of the light source used is also relatively high.

A lamp in accordance with the invention therefore includes an opticalsystem which produces a cruciform light distribution 3 with two mutuallyperpendicular light bars 3 a and 3 b. As the light distribution istotally symmetrical in the bars 3 a and 3 b, a lamp according to theinvention can also be installed in a position of being turned through90° without the light distribution of the light cone which is projectedinto space being markedly altered. As the area of the light bars 3 a, 3b, at any distance from the light source, is substantially smaller thanthat of the associated circular cone cross-section 1, a substantiallylower level of light power is sufficient to achieve the same, prescribedbrightness.

As specified in the photometric regulations for side marking lamps, thelight bar 3 a, with respect to the central light cone axis HV, involvesan extent of 10° upwardly and downwardly respectively and 45° towardsthe left and the right respectively.

In comparison, the vertical light bar 3 b is of a vertical extent of 10°towards the left and the right and a vertical extent of 45° upwardly anddownwardly respectively so that, when the lamp according to theinvention is turned through 90°0, the light bar 3 b can readily performthe function of the horizontal light bar.

FIG. 3 shows an optical system 6 a for a lamp according to the inventionwhich, in combination with an identical optical system 6 b (see FIG. 8)which is arranged beside it and turned through 90°, is in a position toproduce the horizontally and vertically completely symmetrical lightdistribution which is shown in FIG. 2.

Each of the optical systems 6 a and 6 b is formed in a plate-shaped body8 of a transparent material and is of a substantially square shape inthe plan view shown in FIGS. 3 and 8 respectively.

In the direction of view in those two Figures, provided in front of theplate-shaped body 8 for each of the two optical systems 6 a, 6 b is alight source (not shown), preferably a light emitting diode, whichradiates a conical light beam on to the rear side 10 of the body 8,which is towards the viewer, in such a way that the central axis ofsymmetry HV of that light beam impinges on that rear side 10 insubstantially perpendicular relationship and passes through the body 8at the center of the square formed by the respective optical system 6 aand 6 b respectively without a change in direction.

As can be seen in particular from the sectional views in FIGS. 4 through7 the body 8 is substantially in the form of a flat plate withplane-parallel front and rear sides 9 and 10 respectively, in whichrespect however incorporated into the rear sides 10 is a row ofoptically active structures which are described in greater detailhereinafter.

In the present context, the term optically active structure is used todenote any lens-like or prism-like structure which is capable ofchanging the direction of light beams passing therethrough, through apredetermined angle.

Besides those optically active structures, each of the optical systems 6a, 6 b has a plurality of optically inactive regions 12, through whichthe incident light passes without a change in direction.

As can be seen in particular from FIGS. 6 and 7, in this case thevarious regions 12 do not necessarily have to be of the same thickness.The only aspect which is common to them is optical inactivity in theabove-defined sense.

As FIGS. 3 and 8 show the optically active structures of each opticalsystem 6 a and 6 b respectively are arranged along two crossbars 14, 16,the central axes 18, 20 of which cross at the center of the respectivesquare, that is to say at the point of intersection of the central axisHV of the incident light cone.

Admittedly the two arms 14 a, 14 b and 16 a, 16 b respectively of eachcrossbar 14 and 16 are of a symmetrical configuration with respect tothe center just referred to above, but the two crossbars 14, 16 differfrom each other in terms of the optically active individual structuresforming them.

Provided in concentric relationship with the point of intersection ofthe two central axes 18, 20 is a converging lens 22 which focuses thelight impinging thereon in such a way that it produces the requiredbrightness peak in the HV direction.

As the light which is incident from the light source has a level ofbrightness which decreases in an approximately bell-shaped configurationfrom the inside outwardly, the optically active individual elementsadjoining the central converging lens 22 in the crossbars 14, 16 providefor re-distribution of the incident light from regions with a lightexcess at the center of the arrangement and the area immediatelysurrounding same into the further outwardly disposed angular regionswhich involve a light deficiency.

It will be noted that this takes place in different ways in the twocrossbars 14, 16.

As can be seen from the sectional view in FIG. 4 the central lens 22 isof only a relatively small extent in the direction of the crossbar 14 sothat in the plan view in FIG. 3 it appears as a circle which is cut offon two sides, wherein the two secants 23, 24 extend in parallelrelationship with the central axis 20 of the horizontal crossbar 16. Inthe direction of the vertical crossbar 14, adjoining the centralconverging lens 22 on each side and symmetrically relative to the pointof intersection of the central axis HV is an optically active structure26 which is shown in the sectional view in FIG. 4 as a steeply risingprismatic edge surface which distributes the light incident thereonoutwardly while the dome-shaped or lens-shaped, optically active regions27 which immediately adjoin same expand the light impinging thereon anddistribute it over the entire region of the respective crossbar arm 14 aand 14 b respectively.

A respective optically inactive region 12 then outwardly adjoins theoptically active regions 27.

As the sectional view in FIG. 5 shows the central lens 22 is of asubstantially greater extent in the direction of the central axis 20 ofthe crossbar 16 so that here the full circular shape is attained. Then,adjoining the lens 22 on both sides, in symmetrical relationship withthe point of intersection of the central axis HV, are two opticallyactive elements 28, 29 which are both shown in the sectional view inFIG. 5 in the form of rising prismatic edge surfaces, wherein the edgesurface of the optically active element 28 is steeper than that of theoptically active element 29. The two distribute only outwardly the lightincident thereon, similarly to the optically active elements 26.Adjoining the optically active elements 29 on both sides is an opticallyactive element 30, the significance of which is explained hereinafter.

In addition the horizontal crossbar 16 includes optically activeelements 31 which, as can be seen from FIG. 6, are in the form ofsegments of a cylinder, wherein the longitudinal axes of those cylindersextend in parallel relationship with the central axis 20 of thehorizontal crossbar 16. By means of those optically active elements 31light from regions outside the required zones is refracted in such a waythat it is incident in the regions in which an increase in the intensityof light is required.

The vertical crossbar 14 also includes optically active regions 32 (seeFIG. 7) which are in the form of segments of a cylinder and whichperform the same function as the optically active elements 31.

By virtue of the fact that the light source must be at a certain minimumspacing from its associated optical system 6 a (that is to say in frontof the plane of the drawing in FIG. 3) and 6 b respectively, becauseotherwise, with inaccurate positioning, the resulting angular errorsbecome excessively great, the crossbars 14, 16 are not of an identicalconfiguration, as already indicated above. Geometrically, the opticallyactive elements 26 and 27 which are disposed between the opticallyactive elements 32 of the vertical crossbar 14, extending in thelongitudinal direction of the bar, like the optically inactive regions12 thereof, are of the correct width to allow the light to passtherethrough in the required angular region and distribute it in thevertical crossbar 14 respectively.

For geometrical reasons the remaining space, for the horizontal crossbar16, is not sufficient for it to be of the same width so that itsoptically active regions 28, 29, 30 must be narrower, in perpendicularrelationship with the central axis 20. In order to be able to at leastpartially compensate for this, as shown in FIG. 6, provided in theoptically inactive region 12 which is between the optically activeregions 31, 32 is the concave, optically active region 30 which hasalready been mentioned hereinbefore with reference to FIG. 5 and which,as shown in FIG. 7, is not present in the vertical crossbar 14.

The lens effect produced by that concave region 30 provides that theedge region of the cruciform light distribution is better supplied withlight.

As the asymmetrical light distribution, behind each one of the opticalsystems 6 a and 6 b, cannot be completely compensated by the opticallyactive regions 30, in accordance with the invention, for a vehicle lampwhich can be mounted turned through 90° steps, as shown in FIG. 8, twooptical systems 6 a, 6 b are arranged in directly mutually adjacentrelationship and turned relative to each other through 90°, in such away that the central axis 20 of the crossbar 16 of the optical system 6a at the left in FIG. 8 is aligned with the central axis 18 of thehorizontal crossbar 14 of the right-hand optical system 6 b, while thecentral axis 18 of the crossbar 14 of the left-hand optical system 6 aextends in parallel relationship with the central axis 20 of thecrossbar 16 of the right-hand optical system 6 b.

Otherwise, the two optical systems 6 a and 6 b are of an identicalconfiguration, as was described with reference to FIGS. 3 through 7.

The bodies 8 a, 8 b which comprise a transparent material and into therear side of which is incorporated the respective optical system 6 a and6 b respectively are preferably integrally connected to each other andform for example a part of the light transmission cover 10 of thevehicle lamp shown in FIG. 9.

The arrangement of the two optical systems 6 a and 6 b in a common planeand the above-described configuration of the optically active elementsthereof can provide that the light passing through them, after passingthrough a near range which is only a few centimeters, is combined toform a single overall light beam which, at medium and greater distances,is of a cruciform cross-section, the two crossbars involving identicallight distribution effects. The use of two optical systems which arearranged in mutually juxtaposed relationship in that way, each with arespective associated light emitting diode, has the advantage, over acompletely symmetrical configuration of a single optical system withonly one light emitting diode, that the two light emitting diodes haveto be of a substantially lower level of brightness and are thereby lessexpensive than a single light emitting diode which would have a level ofbrightness sufficient for lighting up a cruciform optical system of acompletely symmetrical configuration.

FIG. 9 is another perspective view of a vehicle lamp according to theinvention, wherein two fixing openings 40 are illustrated in addition tothe above-described elements.

1. A vehicle lamp, in particular a side marking lamp for a motorvehicle, comprising at least one light source and at least one imagingoptical system (6 a, 6 b) arranged in the beam path of the light source,characterised in that the substantially conical light beam issuing fromthe light source impinges directly on the imaging optical system (6 a, 6b) and shines therethrough, wherein the imaging optical system (6 a, 6b) is such that it produces therefrom a cruciform light distribution(3).
 2. A vehicle lamp as set forth in claim 1 characterised in that theat least one light source is a light emitting diode.
 3. (currentlyamended): A vehicle lamp as set forth in claim 1 or claim 2characterised in that the imaging optical system (6 a, 6 b) has twoelongate, mutually intersecting crossbars (14, 16) and that the lightsource is so arranged that the central beam (HV) of the light coneissuing therefrom is in substantially perpendicular relationship withthe plane defined by the central longitudinal axes (18, 20) of the twocrossbars (14, 16) and passes therethrough at the point of intersectionof the two longitudinal axes (18, 20).
 4. A vehicle lamp as set forth inclaim 3 characterised in that each crossbar (14, 16) includes aplurality of optically differently active individual structures (26, 27,28, 29, 30, 31, 32).
 5. A vehicle lamp as set forth in claim 4characterised in that at least some of the optically differently activeindividual structures (26, 27, 28, 29, 30, 31, 32) are arranged onebehind the other in the longitudinal direction of the crossbar (14, 16).6. A vehicle lamp as set forth in claim 4 characterised in that at leastsome of the optically differently active individual structures (26, 27,28, 29, 30, 31, 32) are arranged one beside the other in the transversedirection of the crossbar (14, 16).
 7. A vehicle lamp as set forth inclaim 4 characterised in that each of the crossbars (14, 16) has twoarms (14 a, 14 b, 16 a, 16 b) whose optically active individualstructures (26, 27, 28, 29, 30, 31, 32) are of a symmetricalconfiguration and arrangement with respect to the point of intersectionof the longitudinal axes (18, 20) of the crossbars (14, 16).
 8. Avehicle lamp as set forth in claim 3 characterised in that the twocrossbars (14, 16) are of differing widths.
 9. A vehicle lamp as setforth in claim 4, characterised in that the optically active individualstructures (26, 27, 28, 29, 30, 31, 32) of the one crossbar (14) are atleast partially different from those of the other crossbar (16).
 10. Avehicle lamp as set forth in claim 4 characterised in that at least oneof the crossbars (14, 16) includes transparent but optically inactiveregions (12) in addition to the optically active individual structures(26, 27, 28, 29, 30, 31, 32).
 11. A vehicle lamp as set forth in claim3, characterised in that the two crossbars (14, 16) are at leastpartially surrounded by transparent optically inactive regions (12). 12.A vehicle lamp as set forth in claim 3, characterised in that the twocrossbars (14, 16) are in mutually perpendicular relationship.
 13. Avehicle lamp as set forth in claim 3, characterised in that there isprovided a converging lens (22) which is concentric with the point ofintersection of the two longitudinal axes (18, 20) of the crossbars (14,16).
 14. A vehicle lamp as set forth in claim 13 characterised in thatthe converging lens (22) differs from a circular shape insofar as it iscut off on two sides by secants (23, 24) in parallel relationship withthe longitudinal axis (20) of a crossbar (16).
 15. A vehicle lamp as setforth in claim 12, characterised in that it includes two light sourceseach with a respective associated imaging optical system (6 a, 6 b),wherein the two imaging optical systems (6 a, 6 b) are arranged in aplane in mutually juxtaposed relationship in such a way that thelongitudinal axes (18, 20) of two crossbars (14, 16) are aligned witheach other and the longitudinal axes (18, 20) of the other two crossbars(14, 16) extend in mutually parallel relationship.
 16. A vehicle lamp asset forth in claim 15 characterised in that the optically activeindividual structures (26, 27, 28, 29, 30, 31, 32) in at least onecrossbar (14, 16) of the one imaging optical system (6 a) are differentfrom those in the respective identically extending crossbar (14, 16) ofthe other imaging optical system (6 a).
 17. A vehicle lamp as set forthin claim 16 characterised in that the two crossbars (14, 16) of each ofthe two imaging optical systems (6 a, 6 b) have different opticallyactive individual structures (26, 27, 28, 29, 30, 31, 32) and that thetwo imaging optical systems (6 a, 6 b) although of an identicalconfiguration are however arranged turned through 90° relative to eachother.